1. Technical Field
The present invention relates to a weld line-detecting method that facilitates teaching of fillet welding, for example, and relates to an industrial robot.
2. Background Art
Technology where a sensor is disposed in a welding torch and detects a welding position is known in relation to a weld line-detecting method when a welding position is taught to a welding robot before fillet welding (for example, Unexamined Japanese Patent Publication No. S58-176078).
As shown in FIG. 8C, sensor 83 is disposed in a part of the outer periphery of welding torch 82 out of which welding core (welding wire) 81 is projected. When welding torch 82 is located with reference to fillet, welding position P on the Y-Z plane as shown in FIG. 8A, pressing welding torch 82 in the direction of welding core 81 generates bending moment Md in welding torch 82. Sensor 83 detects bending moment Md. The correspondence between the direction of bending moment Md and the position of welding torch 82 is previously set in the welding robot. On recognizing the position based on the direction of bending moment Md, the welding robot moves welding torch 82 toward fillet welding position P. Finally, the position state shown in FIG. 8B is provided. In the state of FIG. 8B, the bending moment does not occur in welding torch 82, and only axial force Fn, namely a force of the direction of welding core 81, is left.